Subminiature rotary switch



Al-JYI 17, 1962 c. HuETTl-:N ETAL 3,030,460

SUBMINIATURE ROTARY SWITCH Filed Sept. lO, 1959 2 Sheets--Sheei l /IVVENTORS CLARENCE HUETE/V, FRED L. RUGERS, JR., FLOYD C. SM/TH.

.BW MW A TTOR/VEX April 17, 1952 c. HUETTEN ET A.`r 3,030,460

SUBMINIATURE ROTARY SWITCH Filed Sept. lO, 1959 2 Sheets-Sheet 2 w /NVE/vrons,

CLARENCE HUETTE/t FRED L. ROGERS, JR.

FLOYD C. MJTH. BY v United States Patent United States of America as represented by the Secretary of the Army Filed Sept. 10, 1959, Ser. No. 839,267 6 Claims. (Cl. 200-11) Ihe present invention relates to a subminiature rotary sw1tch, and more particularly to a switch of this type utilizing spring contact terminals in cooperation with a rotor having printed circuit contacts in two or more circular tracks.

Switches of the type disclosed herein will find great utility in connection with instruments such as radios, tube testers, and other electronic equipment,

For a switch to qualify as a satisfactory subminiature type it is essential that the parts, including the rotor, be very small and at the same maintain low contact resistance, high insulation resistance, and high resistance to voltage ashover or breakdown. In addition, the parts should be easy to manufacture. The requirement that the switch be Very small makes the task of securely fastening the contact elements to the switch rotor and the switch body diicult if not impossible.

For the inner and outer tracks of metallic segments on the rotor to have the best electrical and mechanical properties, they should be placed on the rotor at the largest possible diameter. However, this location of the tracks tends to reduce the contact force and deection characteristics of stator spring terminals by limiting or shortening their length, if conventional mounting techniques used. As these deflection characteristics' are essential for low contact resistance and long life, the means of fastening the terminals must provide the longest possible spring contacts so that satisfactory contact force and deflection characteristics can be obtained while minimizing the amount of radial space used to fasten the spring contact terminals on the stator.

It is a primary object of this invention to provide an eiiicient subminiature rotary switch.

It is a further object to provide a subminiature rotary switch having low contact resistance between spring contact terminals and the rotor contact segments, high insulation resistance between the segments, and high resistance to voltage ilashover or breakdown.

It is another object to provide a subminiature rotary switch having a small rotor which is easy to manufacture.

It is still another object to provide means for mounting the spring contact terminals on the body of a subminiature rotary switch so that they will achieve a satisfactory contact force and deection characteristic for low contact resistance and long life.

To accomplish these and other objects the rotor is fabricated from a copper-clad laminate. The rotor is a thin insulating disc of small diameter, having conductive material applied by printed circuit techniques and formed as two tracks. In each track there are contact segments and island portions, the island portions being between the contact segments to prevent the wiper portions of the spring contact terminals from sliding on the insulation forming the rotor body.

The spring contact terminals are fastened to the plastic switch stator housing in a minimum amount of radial space by the use of longitudinal dovetail grooves in the outer periphery of the housing.

The exact nature of this invention as well as its advantages will be readily apparent from consideration of 3,030,460 Patented Apr. 17, 1962 the following specification taken in connection with the annexed drawings in which:

FIGURE l is a longitudinal sectional view of the preferred embodiment of the subminiature switch;

FIGURE 2 is a view of a portion of the subminiature switch of FIGURE 1 taken on line 2-2 looking in the direction of the arrows;

FIGURE 3 is one embodiment of the rotor;

FIGURE 4 is another embodiment of the rotor;

FIGURES 5A and 5B are side and bottom detail views, respectively, of a spring contact terminal;

FIGURES 6A and 6B are top and side detail views, respectively, showing one of the dovetail grooves in the stator housing;

FIGURE 7 is a top detail view of a spring contact terminal positioned in a dovetail -groove in the stator; and

FIGURES 8A and 8B are side cross sectional detail views, respectively, of a backwardly-folded spring contact wiper and of an extended spring contact wiper, each positioned in a dovetail groove in the stator.

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIGURE 1 a subminiature rotary switch in which the housing is made up of an upper section 11 and lower section 12. Lower section 12 comprises an outer cylindrical stator housing 13 having a plurality of longitudinal dovetail grooves 14 in its outer periphery, as shown in detail in FIG- URES 6A and 6B, for anchoring spring contact terminals 15 and 15. These dovetail grooves 14 permit fastening of the spring contact terminals 15 and 15 to housing 13 using a minimum amount of radial space. Contact terminals 15 and 15 are of two shapes', as

I described in more detail in connection with FIGS. 8A

and 8B below. As both are anchored in the housing in the same manner and have similar basic elements, the discussion in the following paragraphs relates equally to each, and contacts 15 only will be referred t0.

As shown in FIGURES 5A and 5B each spring contact terminal 15 comprises a dovetail retaining section 16, and end portion 17, solder tabs 18, and a spring wiper portion 19 having a contact dimple 21 in the end. When a contact terminal 15 is pushed into a dovetail groove 14, the dovetail retaining section 16 is compressed so that the terminal is rigidly aligned in the dovetail groove. To prevent pulling the terminal out of its groove, end portion 17 is bent over into recess 22 as shown in FIGS. 8A and 8B. This method of fastening the spring Contact terminals through the use of dovetail grooves electively utilizes to the greatest advantage only a small radial portion of the stator. The two solder tabs 18 form an integral part of each spring contact terminal and provide over twice the stiffness of a single tab if the wire leads fo-r external connections pass through and are soldered to both.

As shown in FIGURE l, a bottom plate 23, having a central opening 31 for a passage of a shaft, closes the bottom of stator 13. Attached to this bottom plate and to the inner surface of stator 13 is an insulating washer 24. This washer can also be formed as an integral part of the stator.

Rotor 25 is biased by the spring pressure of terminals 15 into contact with washer 24. An aperture 29 is provided in the center of the lrotor for a shaft 34.

The rotor is made up of a copper clad laminate of insulation having the conductive material on its upper surface formed as an inner track 10 and outer track 20 by printed circuit techniques, such as photoengraving. As shown in FIGURE 3, each track generally comprises contact segments 26 separated by island portions 27. Islands 27 prevent the dimple end 21 of spring wiper portion 19 of terminals- 15-from sliding on the insulation of the rotor body to eventually deposit metal thereon. This would reduce the insulation resistance `and. result in ilashover or breakdown. Additionally, the islands help to reduce Wear by presenting a substantially level Wearing surface to the contact dimples 21, so that they need not ride up over each contract.

The rotor can easily be miass-produced by printed circuit techniques. This manner of fabricating the rotor conserves space Aas compared to riveting metal stampings to the rotor, and eliminates the handling and assembly of m-any tiny parts to the rotor.

In designing a rotor of this type any of the contact segments 26 may be used'` individually, or in combination, with islands 27 to form contact elements. When desired, conductive material can be added in any of the areas marked X to form continuous arcs of conductive material as extensive as .necessary for the particular switching application.

As shown in FIGURE 1, the spring wiper portions 1.9 of the spring contact terminals 15 may have at least twotshapes depending on the rotor trackto be contacted. FIGURES 8A and 8B show these shapes in more detail, the corresponding parts of. the contact terminals of FIG. 8A being primed to distinguish them from FIG. 8B. The spring. wiper portions 19' of Contact termintals'lS are bent backwardly as in FiGURE 8A to engage the outer circle of contacts 20, while the portions 19 of contacts 15 are extended to engageA the inner circle of contacts as in FIG. 8B. Eachy end dimple 2l or 21 has la at portion of sufficient length to bridge from a contact segment to an island portion.

At least two dovetail slots 32 are provided in the outer periphery of stator 13 for fastening side rods 33 of upper section 11. This permits the upper and lower sectionsof the switch housing to be securely interlocked.

Shaft 34 is journalled in bushing 4G of upper housing section 11, and passes through aperture 29 and opening 3.1. Portion 34 extends beyond the bushing for attachment of a knob or other actuating means. Ring 35 its in circumferential slot 36 to retain shaft 34 in upper section 11. Washer 37 xed to shaft 34 prevents its movementv outward. Hexagonal index cam 38, attached to shaft 34, cooperates with parallel flat index springs 39 to forma deten-t mechanism having long life. Moveable stop 41 on washer 37, attached to the shaft, limits the rotation of the shaft.

Panel sealing washer 42 prevents direct contact between the switch and the panel in which it is mounted. This. washer, along with a ring seal 40, provides a shaft and panel hermetic seal in a minimum of space.

The particular subminiature switch shown in FIGURES l and: 2 is a one-pole, six position type. rotor of the type shown Vin FIGURE 4, -a single spring contactterminal of the type shown in FIGURE 8B, and five spring contact `terminals of the type shown in FIG- URE 8A.` The rotor of this switch, yas shown in FIG- URE 4, has its inner track 10 formed as a continuous loop of conductive material and its outer track Zitto-rmed as contact segments 26 and islands 27. A tab 28 electrically connects inner track 1t) to onev of the contact segments 26 of outer track 20.

If it is desired that a plurality o-f switches be operated by a single shaft, additional rotor wafers and additional spring contacts can be added using the techniques described. The length of the switch can be increased as needed.

In summary, the disclosed subminiature rotary switch 'achieves its small size by forming the rotor of a photoengraved copper-clad laminate and by mounting lthe spring contact terminals in longitudinal dovetail grooves in the cylindrical stator housing. This particular manner of mounting the spring contact terminals permits 'them to achieve a satisfactory contact force yand deiec- Ation characteristic for low contact resistance and long It utilizes a v 4 contact life while maintaining a small switch diameter. The use of island portions between the contact segments prevents the spring wiper portions from rubbing on the insulating material, insuring high insulation resistance between the contact segmentsandl'iigh resistance 'to voltage fiashover. Finally, the photoengraving techniques permit these very smallV rotors tofbe easily mass-produced.

The foregoing disclosure relates to a preferred ernbodiment of the invention. Numerous modifications or alterationsmay be made therein without departing from the spirit and scope of the invention set forth in the appended claims.

What is claimed is:

1. A subminiature rotary switch comprising a cylindrical stator having longitudinal dovetail grooves in its outer periphery, spring contact terminals, mounted in said dovetail grooves each of said terminals having spring wiper portions extending inside said stator,l a wafer type rotor having two concentric rings of printed-circuit Vcontaots positioned within said stator, at least one of said spring wiper por-tions extending directly from said stator to make electrical contact with the innermost of said concentric rings of contacts, the remainder of said spring wiper portions being U-shaped and extending from` said stator to make electrical contact with the outermost of said concentric rings of contacts.

2. A subminiature rotary switch comprising an insulating cylindrical stator housing having longitudinal termi-V nal-.retaining dovetail grooves and longitudinal assembly dovetail grooves in its outer periphery, said terminalretaining grooves having adjoining recesses; spring con- -tact terminals having spring-biasing portions retained bysaid terminal dovetail grooves and end portions folded into said recesses, said spring-contact terminals also havi ing wiper portions; a rotor of insulating material having a plurality of circular tracks for engagement by said wiper portions, said tracks comprising contact segments and island portions between contact segments to prevent said wiper portions from sliding on the insulationV forming the rotor, said. rotor having a center apenture; means for rotating said rotor positioned within said aperture, and means engaging said assembly dovetail groovesfor supporting saidr l-ast named meansv in such stator.

3. A subminiature rotary switch having alower section and an upper section, said lower lsection comprising an insulating cylindrical stato-r housing having longitudinal terminalretaining dovet'ail grooves 'and longitudinalv assembly dovetail grooves in its outer periphery, said terminal-retaining grooves having adjoining radial recesses, spring contact terminals having spring-biasing portionsjretained by said terminal dovetail grooves and end portions` folded into said recesses, said spring contact terminals also having wiper portions and solder tabs, a rotor of insulating material having a plurality or" circular tracks for engagement by said Wiper portions, said tracks comprising contact segments and island portions, between contact segments to prevent said wiper portions from sliding on the insulation forming, the rotor, said rotor having -a center aperture, a bottom plate closing the bottom of said stator, an insulating washer positioned between said rotor and said bottom plate; and said upper section comprising an outer casing having vside rods, said side rods being retained by said longitudinal assembly dovetail grooves permitting said upper and lower `scctions to be lsecurely interlocked, a shaft positioned with in said casing having an end passing through said aperture of said rotor, means positioned between said shaft and said casing to permit a hermetic seal, an indexing means attached to said shaft, yand means attachedto said shaft. for limi-ting the rotation of said shaft.

4. A subminiature rotary switch comprising a rotor of' insulating material having la central-aperture and inner and outer circular printed circuit tracks coaxial with s-aid aperture, said tracks comprising contact segments and island portions between said contact segments and. in

close proximity thereto; and 'a cylindrical stator housing of insulating material surrounding said rotor, said stator having a plurality of dovetail grooves in its outer periphery, said grooves having adjoining recesses, first and second types of spring contact terminals having springbiasing portions retained by said dovetail grooves and end portions folded into said recesses, said spring contact terminals also having wiper portions biased into contact with said tracks, the spring wiper portions of said rst type of spring contact terminals being bent backwardly to engage said outer track, the spring Wiper prtions of said second type of spring contact terminals being extended to .engage said inner track; and means positioned in said aperture for rotating said rotor.

5. The subminiature rotary switch of claim 4 in which said inner tnack is formed as a continuous loop of conductive material yand is electrically connected to one contact segment of said outer track.

6. In a subminiature rotary switch: a rotor, a cylindrical stator surrounding said rotor and having longitudinal grooves in its outer periphery, said grooves having adjoining recesses at one end of said cylindrical stator, and a plurality of unitarily constructed contact terminals each comprising a pair `of solder tabs, a retaining section, an end portion Iat one end of said retaining section, and

a spring wiper portion at the end of said retaining section opposite said one end; each of said retaining sections being situated in one of said longitudinal grooves, said end portions being folded into said recesses, said spring wiper portions being folded around said cylindrical rotor at the end thereof opposite said recesses so that said contact terminals are rigidly fastened to said stator by said end portions and said spring wiper portions, said spring wiper portions extending retrorsely inside said stator and contacting said rotor.

References Cited in the file of this patent UNITED STATES PATENTS 1,504,283 Taylor Aug. 12, 1924 1,704,625 Nero Mar. 5, 1929 1,738,140 Despard Dec. 3, 1929 2,678,985 Smith May 18, 1954 2,777,118 Sundt Jan. 8, 1957 FOREIGN PATENTS 108,034 Sweden July 27, 1943 1,127,588 France Aug. 13, 1956 1,128,738 France Aug. 27, 1956 1,093,845 Germany Dec. l, 1960 STATES PATENT OFFICE E OF CORRECTION April 1T, 1962 UNITED CERTIFICAT Clarence Huetten et al.

rtfied that error appears in the a on and that the said Letters Patent s It is hereby ce ent requiring correet corrected below.

lines 33 and 34, s" insert after "technique ke out, the

"terminals" str Column l, are column 4, Ine 16, after comma; Ine I7, after "grooves" insert a comma.

y of October 1962.

Signed and sealed this 9th da (SEAL) DAVID L. LADD Attest:

Commissioner of Patents ERNEST W. SWIDEF. Attestng Officer 

